A. Material preparation
Para rubber seed discarded from agricultural process was supplied from Surat Thani province in
southern of Thailand. It was separated two parts, shell from grinding process and residue from extraction
process. They were dried at 120 C an overnight for humidity controlled lower than 5%. Then, dried shell
was sized on 1.13 and 2.18 mm but could not for residue because its structure was very soft. Both of shell
and residue were analyzed in proximate analysis as showed in Table 1 and kept in desiccators.